Determine the preferred initial mass function for Type Ia supernova host-galaxy masses

Determine whether the Kroupa or Chabrier initial mass function is preferable for measuring Type Ia supernova host-galaxy stellar masses, given that current evidence does not establish a clear preference between them.

Background

Host-galaxy stellar-mass estimates depend sensitively on the assumed stellar initial mass function (IMF), particularly because the Salpeter IMF predicts substantially more low-mass stars than the Kroupa and Chabrier alternatives. The analysis compares Kroupa-, Chabrier-, and Salpeter-based stellar masses and finds that Kroupa and Chabrier choices produce broadly consistent cosmological results.

The paper nevertheless states that there is no clear preference between the Kroupa and Chabrier IMFs. Establishing which IMF is physically and observationally best justified would improve the interpretation and consistency of host-galaxy stellar-mass measurements used in Type Ia supernova cosmology.

References

There is not a clear preference between the Chabrier IMF and the Kroupa IMF, meaning they are both widely used currently; we note that the difference between the Kroupa and Chabrier IMFs at the low-mass end is quite small.

— Supernovae Unite: Host-Galaxy Mass Measurements of Type Ia Supernovae and Their Impact on Cosmology  (2609.05321 - Lee et al., 4 Sep 2026) in Section 4.1.1, “Which Initial Mass Function?”